3-5.c

#include<stdio.h>

int main() {
    printf("[1] apple\n"
           "[2] pear\n"
           "[3] orange\n"
           "[4] grape\n"
           "[0] exit\n"
    );

    int a, k;
    for (a = 0; a <= 4; a++) {
        scanf("%d", &k);
        if (k == 0) {
            break;
        }
        switch (k) {
            case 1:
                printf("price = 3.00\n");
                break;
            case 2:
                printf("price = 2.50\n");
                break;
            case 3:
                printf("price = 4.10\n");
                break;
            case 4:
                printf("price = 10.20\n");
                break;
            default:
                printf("price = 0.00\n");
                break;
        }
    }

    return 0;
}